I have suggested what Rashid said to one of my chapters in my district. I actually have two chapters in my district who are the sorority's largest chapters; Chi at the University of Georgia had 220 sisters last year and Epsilon Beta at Clemson had over 150 sisters last year. They were having issues too with having TOO MUCH interest, so I suggested they have a Fall Rush and nothing for the Spring. It worked well for them.
They're still the largest two we have though